1. Field of the Invention
The present invention is directed to automated manufacturing of fiber optic components. More specifically, the present invention is directed to apparatus and methods for processing two or more optical fibers.
2. Description of Related Art
During processing and manufacture of optical components such as overclad fiber optic couplers, two or more optical fibers need to be conveyed parallel and in close proximity to one another. More specifically, overclad fiber optic couplers are a type of fused fiber coupler wherein the coupling region is enclosed within a layer of matrix glass. To form an overclad fiber optical coupler, the stripped portions of a plurality of fibers are inserted into the bore of a glass capillary tube to form a coupler preform. The tube bore typically has enlarged funnel-shaped end portions that facilitate the insertion of optical fibers. The mid region of the coupler preform is heated to collapse the glass tube onto the fibers and then, the coupler preform is stretched until the desired coupling characteristics are obtained. Various types of overclad fiber optic couplers and methods of making such couplers are disclosed in U.S. Pats. No. Re. 35,138, U.S. Pat. Nos. 4,902,324, 4,979,972, 5,011,251, 5,251,276 and 5,268,014. To manufacture such optical couplers, regions of the optical fibers have to be stripped and inserted into the tube forming a coupler preform. A portion of the coupler preform is heated and collapsed onto the stripped portion of the optical fibers. The collapsed portion of the preform is then drawn to form a coupling region between the optical fibers. After the optical coupler has been formed by stretching the overclad tube and fibers, a glue such as an ultraviolet (UV) curable epoxy is inserted into the uncollapsed ends of the glass tube bore to provide the fibers with pull strength.
To facilitate manufacture of such optical components, an improved apparatus and manufacturing method has been disclosed in U.S. Pat. No. 6,092,394 to Backer et al. which discloses an automated manufacturing process for fiber optic couplers. In this regard, the apparatus disclosed in Backer et al. utilizes fiber feed mechanisms to route optical fibers to various processing stations. For instance, a plurality of optical fibers are fed to a station that strips a protective coating from a portion of one or more of the optical fibers. The optical fibers are also fed through the bore of the glass tube and the stripped portions of the optical fibers precisely positioned relative to one another to provide the coupler preform described. After the coupler preform is formed it is heated and drawn to form the fiber optic coupler. In order to precisely position the stripped portions of the optical fibers in the bore of the glass tube, the disclosed fiber feed mechanism allows feeding of the optical fibers independently from one another. It has been found that better quality couplers can be made at a greater rate and with more consistency using the invention of Backer et al., than can be made by the aforementioned manual process.
However, as described in further detail herein below, several limitations have been found by the present inventors in the apparatus and method disclosed in Backer et al. which limit the automation capacity of the disclosed apparatus and method.
In using the apparatus and method disclosed in Backer et al., the present inventors have found that occurrences of misfeed or other mishandling of one or more of the optical fibers occurred due to their proximity of the optical fibers to one another. In particular, the present inventors found that due to the close proximity of a plurality of optical fibers to one another during optical fiber processing or optical component manufacturing, the fibers have a tendency to cling to one another. The clinging of optical fibers to one another makes it difficult to feed the ends of each of the optical fibers to the desired location or proper position. For example, due to the clinging of optical fibers, each fiber may be improperly fed to a wrong roller in a subsequent fiber feed mechanism. When this occurs, the optical coupler manufacturing process is interrupted and an operator must manually correct the situation by pulling the misfed optical fiber out and feeding it to the proper location or position.
Furthermore, the close proximity of the optical fibers to one another has also posed another difficulty in fully automating the manufacture of overclad fiber optic couplers. In particular, because a portion of one or more of the fibers need to be stripped as previously described, the optical fiber to be stripped needs to be separated from the rest of the fibers. Otherwise, when the protective coating is removed using a hot, gaseous stripping medium, the hot stripping medium such as nitrogen gas impinges on the other fibers thereby stripping the protective outer covering at improper locations on these optical fibers.
In view of the foregoing, the present invention has the advantage of providing a reliable apparatus and method for separating a first optical fiber from a second optical fiber.
Another advantage of the present invention is in providing such an apparatus and method which will allow proper feeding of a fiber end to a desired location or position for further processing.
Still another advantage of the present invention is in providing such an apparatus and method which will allow separation of the second fiber away from the first fiber that is to be stripped.
In accordance with one embodiment of the present invention, an apparatus for separating a first optical fiber from a second optical fiber is provided, the apparatus including a fiber feed mechanism adapted to feed the first optical fiber and the second optical fiber, and a nozzle adapted to provide a displacing force on the second optical fiber, where the second optical fiber is displaced away from the first optical fiber thereby separating the second optical fiber from the first optical fiber. In accordance with one embodiment, the displacing force is directed away from the nozzle while in another embodiment, the displacing force is directed towards the nozzle. The displacing force is provided by a gas stream in one embodiment. The fiber feed mechanism in accordance with one embodiment is further adapted to selectively feed the first optical fiber and the second optical fiber independently of each other.
In accordance with another embodiment of the present invention, the apparatus for separating a first optical fiber from a second optical fiber further includes a separation mechanism positioned a spaced distance from the fiber feed mechanism in a manner that the nozzle is positioned between the fiber feed mechanism and the separation mechanism, the separation mechanism including a first guide and a second guide spaced apart from one another, where the first and second guides receive the first and second optical fibers respectively. A guide separator is further provided between the first guide and a second guide in accordance with one embodiment. In addition, in another embodiment, the displacing force is exerted on a tip portion of the second optical fiber prior to the second optical fiber being received in the second guide. In this regard, the nozzle is positioned proximate to the separation mechanism in a manner that the displacing force displaces the tip of the second optical fiber towards the second guide to allow insertion of the second optical fiber into the second guide. In one embodiment, a deflector plate positioned to limit the displacement of the tip of the second optical fiber is also provided, the deflector plate including a vent opening including a plurality of through holes. The deflector plate is further adapted in another embodiment to guide the tip of the second optical fiber into the second guide and includes a concave surface.
In still another embodiment, the apparatus further includes a retainer where a first segment of the first optical fiber and a second segment of the second optical fiber are retained between the fiber feed mechanism and the retainer, length of at least the second segment being extendible by feeding additional length of the second optical fiber via the fiber feed mechanism. In this regard, the retainer of one embodiment is a clamp mechanism having a first clamp pad and a second clamp pad, at least one of the first and second clamp pads being transversely displaceable relative to the other to allow clamping of the first optical fiber and the second optical fiber thereinbetween. Preferably, the first clamping pad includes an offset extension that extends beyond an edge of the second clamp pad in a manner to predispose the second segment of the second optical fiber away from the offset extension when the second optical fiber is clamped in the clamp mechanism and extended via the fiber feed mechanism. Moreover, the displacing force acts on a mid portion of the second segment as the second optical fiber is extended via the fiber feed mechanism.
In accordance with another aspect of the present invention, a method for separating a first optical fiber from a second optical fiber is provided including the steps of providing a fiber feed mechanism adapted to feed the first optical fiber and the second optical fiber in a manner that the first optical fiber and the second optical fiber are parallel to one another, and exerting a displacing force on the second optical fiber to physically displace the second optical fiber away from the first optical fiber to thereby separate the second optical fiber from the first optical fiber. In accordance with one embodiment, the displacing force is provided by impinging a gas stream on the second optical fiber. In one embodiment of the present method, the fiber feed mechanism is further adapted to selectively feed the first optical fiber and the second optical fiber independent of each other.
In accordance with another embodiment, the present method also includes the step of inserting the first optical fiber into a first guide and inserting the second optical fiber into a second guide, the first guide being spaced apart from the second guide. In this regard, the present method also includes the step of displacing a tip portion of the second optical fiber towards the second guide prior to the step of inserting the second optical fiber into the second guide. Moreover, the present method of another embodiment further includes the steps of inserting the first optical fiber into the first guide before exerting the displacing force on the tip portion of the second optical fiber. In accordance with still another embodiment, the present invention further includes the step of limiting displacement of the tip of the second optical fiber by providing a deflector plate that limits physical displacement of the tip of the second optical fiber.
Yet another embodiment of the present method further includes the steps of retaining the first optical fiber and the second optical fiber in a manner to provide a first segment of the first optical fiber and a second segment of the second optical fiber, and extending length of at least the second segment by feeding additional length of the second optical fiber via the fiber feed mechanism. In accordance with one preferred embodiment, the step of retaining the first optical fiber and the second optical fiber are attained by a clamp mechanism, the clamp mechanism including a first clamp pad and a second clamp pad, at least one of the first clamp pad and the second clamp pad being transversely displaceable relative to the other to allow clamping of the first optical fiber and the second optical fiber thereinbetween. In this regard, one embodiment further includes the step of providing the displacement force on a mid portion of the second segment as the second segment is extended via the fiber feed mechanism. The step of maintaining the extended second segment away from the first segment is obtained in one embodiment by continually exerting the displacing force on the a mid portion of the second segment. In another embodiment, the first clamping pad includes an offset extension that extends beyond an edge of the second clamp pad in a manner to predispose the second segment of the second optical fiber away from the offset extension when the second optical fiber is clamped in the clamp mechanism.